Noise spectra of three-dimensional random metal-insulator composites

We report on measurements of low-frequency noise in percolating AgPt-tetrafluoroethylene metal-insulator composites. For all samples, the excess noise showed a 1/f frequency dependence, and the magnitude of the noise scaled with $V^2$. In addition, the magnitude of this noise was linearly proportional to the sample resistance R far from the percolation threshold, but increased more rapidly as the critical volume fraction was approached, with $S_v$(f) varying approximately as $R^3$ near the transition.